Numerous means exist for removing particle matter from atmospheric air before introducing air into a heating, venting and/or air conditioning system. Usually these systems have one or more removable and replaceable rigid filter elements that are manufactured to a specific length and height and being that are inserted into a channeled filter housing to effectively seal the unit from the introduction of dust, dirt, and pollen.
Over time the filter element will be periodically replaced due to the build up of contaminants on the filter media that requires the technician to purchase a filter element from the original equipment manufacturer or some third party supplier whose sole business is manufacturing generic filter elements.
This system leaves the technician with little choice but to stock every conceivable filter element and to carry them around from job site to job site or order the replacement filter element and schedule a second on-site maintenance call to install the element when it arrives.
Not only does this cost the service technician by having to visit the same site twice and having to perform certain functions twice, but also is an inconvenience to the client, having to shut the system down again. There is also the case of being unable to find or order the filter cartridge due to the age of the equipment, thereby requiring the installation of a filter cartridge that almost fits, which further stresses an aged system that will require more frequent maintenance visits and more time to remove the inevitable buildup of dirt and debris from within the system that is entering from around the edges of an ill fitting filter cartridge. Customers can't or won't understand why their system performance is so poor and feel that their service bureau is more interested in selling them a new system rather than maintaining the one they have.
Additionally, the replaceable rigid filter elements allow significant contaminated, un-cleaned airflow to circulate around the replaceable rigid filter elements due to variations in tolerances of the replaceable rigid filter elements and the original equipment manufacturer's channeled filter housing. This bypass forces the technician to mechanically clean the original equipment manufacturer's air conditioning system and the attached ductwork and air distribution registers more frequently than necessary if proper air seal integrity were achievable and is detrimental to the mechanical and thermodynamic efficiency of the original equipment manufacturer's air conditioning system.
Further, the standard practice of employing a cardboard superstructure to give rigidity to replaceable filter element described in the prior art causes the rigidity to deteriorate during high humidity conditions or rainstorms. Thus, producing situations in which the replaceable rigid filter element is drawn out of the original equipment manufacturer's air conditioning system channeled filter housing and into the air moving fan, therefore destroying the replaceable rigid filter element's ability to filter at all. The use of this cardboard superstructure also blinds a portion of the replaceable rigid filter element and reduces the capacity of the element to capture and retain particulate matter. Finally, the use of this cardboard superstructure demands the use of wood fiber and is not environmentally conservative.
Therefore, it is felt that the need exists to provide the technician with the ability to fabricate the needed filter element on-site, on an as-needed basis and in a custom size providing a positive seal, eliminating the reliance on cardboard for rigidity all of which will reduce system maintenance, improve equipment performance, foster good customer relations, and assist in conserving valuable forest resources. Prior art reference includes Beier U.S. Pat. No. 6,214,076; Culwell U.S. Pat. No. 6,152,980; and Stein U.S. Pat. No. 5,968,217.
A need also exists to establish a method of manufacture by which the custom sized, expandable filters can be produced efficiently and cost effectively.